ABB ACS 800 Series, Firmware Manual

Page: 198 / 340

Actual signals and parameters
198
42.10 LOW REF BRK HOLD Activates a brake hold function and defines the hold delay for it. The function
stabilises the operation of the brake control application when the motor
operates near zero speed.
0.0 … 60.0 s 0.0 s = inactive.
0.1 s … 60.0 s = active. When the absolute value of the motor speed reference
falls below the brake close speed:
- The brake is closed according to the normal stop routine of the brake control
function
- The brake hold delay counter starts after the brake close delay.
During the delay, the function keeps the brake closed despite the speed
reference value and the value of the Start command. When the set delay has
passed, the normal operation resumes if the absolute speed reference is
greater than the brake close speed.
The following figures explain the two different scenarios that can occur in the
LOW REF BRK HOLD function. 100 = 1 s
Case 1: The absolute speed reference goes above the brake close speed
before the Low Ref Brk Hold time has elapsed.
Case 2: The absolute speed reference goes above the brake close speed after
the Low Ref Brk Hold time has elapsed. The brake is opened only after the
speed reference goes above the brake close speed. In this case the brake
immediately opens when the speed ref is greater than the brake close speed,
because the LOW REF BRK HOLD time has already elapsed.
* This time is the additional delay until the speed ref goes above the brake
close speed.
Index Name/Selection Description FbEq
t
Internal Speed Ref.
LOW REF BRK HOLD
BRAKE OPEN CMD
BRAKE CLOSE SPEED
t
Speed Ref.
t
BRAKE CLOSE DELAY
BRAKE OPEN DELAY
t
Internal Speed Ref.
LOW REF BRK HOLD
BRAKE OPEN CMD
BRAKE CLOSE SPEED
t
Speed Ref.
t
BRAKE CLOSE DELAY
*
BRAKE OPEN DELAY